The World Wide Web has become a primary source of information useful in everyday life, such as news, stock quotes, weather forecasts, product prices and the like. The World Wide Web and other portions of the Internet utilize an application-level protocol, known as the Hypertext Transfer Protocol (HTTP), which is based on a client/server architecture. The HTTP protocol is described in greater detail in "Hypertext Transfer Protocol--HTTP/1.0," Network Working Group, May 1996, &lt;http://www.ics.uci.edu/pub/ietfhttp&gt;, which is incorporated by reference herein. Many people use bookmark features of a web browser program to store Uniform Resource Locators (URLs) which identify web sites they access frequently. However, the explosive growth in the popularity of the World Wide Web has led to increased Internet congestion and has overloaded many web servers, making it more difficult to obtain desired information within a reasonable time.
A number of techniques have been proposed to provide user-transparent fault tolerance and load balancing by using more than one server to serve the same URL. An exemplary client-side approach, referred to as Smart Client, is described in C. Yoshikawa, B. Chun, P. Eastham, A. Vahdat, T. Anderson and D. Culler, "Using Smart Clients to Build Scalable Services" Proceedings of USENIX 1997 Annual Technical Conference, Anaheim, Calif., Jan. 6-10, 1997, which is incorporated by reference herein. The Smart Client approach involves a service providing an applet running at the client site. The applet makes requests to several mirror sites to collect information about server loads and other server characteristics, and forwards each service request to an appropriate server based on that information. Fault tolerance and scalability are implemented at the client site. Other techniques include, for example, a server-side DNS approach which implements server load balancing in the domain name to Internet Protocol (IP) address translation process, as described in T. Kwan, R. McGrath and D. Reed, "NCSA's World Wide Web Server: Design and Performance, IEEE Computer, pp. 68-74, November 1995, which is incorporated by reference herein. A server-side single-address image approach known as network address translation is described in greater detail in E. Anderson, D. Patterson and E. Brewer, "The Magicrouter, an Application of Fast Packet Interposing" Symposium on Operating Systems Design and Implementation, OSDI, 1996, &lt;http://www.cs.berkeley.edu/.about.eanders/magicrouter/osdi 96-mr-submission.ps&gt;, and Cisco Local Director,&lt;http://www.cisco.com/warp/public/751/lodir/index. html&gt;, both of which are incorporated by reference herein.
A significant problem with the above techniques is that they are generally service-centric, that is, developed from a service provider point of view and with the interests of specific services in mind. As a result, the techniques generally do not allow users to exercise a sufficient amount of control over the manner in which the enhanced availability is provided. For example, the above techniques do not allow a user to customize an access mode to obtain information from multiple sites providing similar information but maintained by different service providers. Other techniques which attempt to alleviate this problem are described in, for example, C. Weider and P. Deutsch, "A Vision of an Integrated Information Service" Network Working Group, RFC 1727, December 1994; B. Ladd, M. Capps, P. Stotts and R. Furuta, "Multi-Head Multi-Tail Mosaic: Adding Parallel Automata Semantics to the Web" Fourth International World Wide Web Conference, 1995; C. L. Brooks, M. Mazer, S. Meeks and J. Miller, "Application-Specific Proxy Servers as HTTP Stream Transducers" Fourth International World Wide Web Conference, 1995; and C. L. Brooks, "Wide Area Information Browsing Assistance Final Technical Report" The Open Group Research Institute, September 1996, all of which are incorporated by reference herein. However, these and other similar techniques typically do not allow users to group several individual HTTP requests into a set such that the set can be conveniently accessed by a single name. Moreover, these techniques can be difficult to integrate with standard browser programs, and generally do not provide an adequate range of user-customizable display formats which can be tailored to facilitate response comparison in on-line shopping and other important applications.
It is therefore apparent that a need exists for improved techniques for accessing information over the Internet and other communication networks, without the problems associated with the above-described conventional approaches.